Many electrophotographic copiers, digital copiers, laser printers, and the like contain an electrophotographic photoreceptor wherein a photoconductive layer is provided on a rotatable drum-like substrate. The substrate may be made by machining the surface of a pipe, and a cutting fluid is normally used in this process. The cutting fluid is used to cool, lubricate, and clean the substrate. Many current processes for machining photoreceptor substrates use a petroleum-based cutting fluid.
For inspection purposes and to prepare the substrates for final cleaning and coating of photoconductor layers, the substrates are cleaned after machining to remove residual cutting fluid. Typically, petroleum residues on a substrate are removed with an ultrasonic vapor degreaser using a chlorine solvent, such as, for example, 1,1,1-trichloroethane, trichloroethylene, perchloro-ethylene, methylene chloride, and the like. However, the use of such solvents can cause problems of environmental contamination and working safety from the viewpoint of ozone layer destruction, carcinogenicity and the like.
Alternatives to chlorine-containing solvents include aliphatic hydrocarbons such as kerosene or strong acid-based detergents. However, these alternatives can present new problems including fire risks and waste neutralization.
A preferred alternative to chlorine solvents would be an aqueous cutting fluid which could be cleaned with a neutral aqueous cleaner. A number of commercial aqueous cutting fluids (e.g., Parker-Amchem 718, TrimMist, Hysol, TrimSol) have been found to be unsatisfactory. A major problem with these cutting fluids is that they either attack metal on the surface of the substrate or alter the substrate surface chemistry, especially with aluminum substrates, so that the substrate has the undesirable characteristic of wetting after subsequent cleaning. Also, such cutting fluids have poor water-break characteristics. These poor properties can result in incomplete coating of the substrate by the cutting fluid and the retention of contaminants on the substrate surface following cleaning, including the retention of water beads. Such defects lead to the rejection of an unacceptably large number of substrates as substrates for receiving photoconductor coatings.
Known cutting fluids do not include or suggest the use of the combination of materials of the aqueous based cutting fluids of the present invention, which achieve surprising performance results as discussed herein. A TrimMist Product Information Sheet discloses a cutting fluid concentrate comprising amine borate, propylene glycol, amine carboxylate, nonionic surfactant, nonsilicone, anti-foam agent and water. In Section 4 of the Product Information Sheet, it is disclosed that the pH of the concentrate is 8.3, and that when diluted to a 10% solution, the pH increases to 8.6. There is no disclosure or suggestion to use a polysiloxane surfactant, or to adjust the pH to a range of from 7.0 to 8.0.
Gililland, U.S. Pat. No. 3,000,826, discloses a metal working lubricant comprising polyethylene or polypropylene glycol, water, and an anti-rust material that is a combination of an alkali metal nitrite and an aliphatic alkanol amine. Gililland does not disclose or suggest the use of a surfactant, much less a polysiloxane surfactant, and in fact teaches that cutting fluids containing surfactants are inferior in performance to the cutting fluid disclosed.
King, U.S. Pat. No. 3,719,598, discloses an aqueous cutting fluid comprising the reaction product of a boric acid and an aliphatic amine, a petroleum sulfonate, and a non-ionic wetting agent. King indicates that the cutting fluid is excellent in corrosion protection. King does not disclose the use of a polysiloxane surfactant or a lubricant such as polyethylene glycol.
Remus, U.S. Pat. No. 4,769,162, discloses a water based lubricant for a conveyor. No mention is made of aqueous based cutting fluids. The composition of the lubricant comprises an anionic surfactant, water or solvent, and an aluminum salt. Optionally, a weak acid may be added in an amount to adjust the pH to between 4 and 6 in order to prevent formation of aluminum hydroxides. Remus does not disclose or suggest a cutting fluid within a pH range of 7 to 8, nor the use of a polysiloxane surfactant in such cutting fluid.